The present invention relates to irrigation sprinklers and pertains particularly to an improved water velocity control disc for an inlet flow check valve assembly of a pop-up sprinkler unit.
The use of irrigation systems for watering plants where rainfall is inadequate is in wide use throughout the world today. One of the most widely used systems, particularly for lawn areas and playing or athletic fields, is the sprinkler system wherein a plurality of pop-up sprinkler units are positioned about a land area for distributing water over the surface of the land area. These units have a riser which retracts into a fixed subsurface housing when not in use. When water is supplied to the unit, the riser extends or pops-up from the underground housing into a position to distribute water.
Sprinkler units of this type are widely used on golf courses and other turf applications. These are usually high pressure systems and are frequently subjected to significant forces each time water is supplied to them, particularly when they are subjected to high pressure air or water. These high forces over a lifetime of use can damage sprinkler units and reduce their useful life. The highest forces result when a sprinkler unit is subjected to surge conditions, such as when the system is being winterized or being refilled with water in the spring. In climates where irrigation systems are subject to freezing, the water must be removed from the system before winter. The water is purged from the system by means of compressed air. The compressed air acts much more rapidly than water and usually results in the risers shooting up rapidly with very high forces resulting in damage to the sprinkler units.
These high forces also frequently occur when empty pipes are being filled with water. As the lines are being filled, air or a combination of water and air is forced into each sprinkler unit and vented through the same. Under these conditions the riser frequently shoots up at a high velocity and is slammed against the stationary housing with relatively great force.
Attempts to solve this problem by making the sprinkler units heavier and stronger have been unsatisfactory because of increased costs. The dual medium of water and air makes unsatisfactory the use of slow opening valves to control the out-flow.
Another problem frequently encountered in sprinkler units is that large particles get trapped between the valve and seat during closing of the valve. This results in continuous leakage until the sprinkler unit is cycled again.
Therefore, there is a need for means for reducing the extension velocity of the riser in order to prolong the life of pop-up sprinkler units. There is also a need for a sprinkler unit design that reduces the tendency for large particles to become trapped on the valve seat.
Accordingly, it would be desirable that a sprinkler unit be available having means for reducing the riser extension velocity to prevent the resultant high forces and consequential damage. It would also be desirable that a sprinkler unit have some means for reducing the tendency for large particles to become trapped on the valve seat.